If you have the authority to solve the biggest issue in the world, which is the one you feel and solve it?

I would only work for Education for all. May be other will be solved automatically if education goes to everybody.

Definitely poverty. In most times, poverty leads to violence.

Injustices.

No Justice, No Peace.

Poorness

Fair opportunity to expression and action,, but such a utopia is our image of heaven. If expression gets a fair opportunity, all will be heard, if action gets a fair opportunity, a lot of good people will act. Evil never succeeds in a fair world,it always has to cheat its way to an unfair advantage.

Corruption

Agree with everyone's reply

Bad politics and politicians.  It is the reason for corruption, poverty, poor economy, war, unhealthy environment, instability, lack of education and advancements, radical laws, and extremism. Take the bad politicians out and you can start to restore world peace. 

Terrorism and would work for Global peace.

Humanity

Education for all